Electrical transmission of colored pictures



Oct. 10, 1933. H. w. JOY 1,929,589

ELECTRICAL TRANSMISSION OF cm-ontn. PI'cg'UaEs FiI'ed July 30, 1928 2Sheets-Sheet 1 00k. 10, 1933. w, JOY 1,929,589

ELECTRICAL TRANSMISSION OF COLORED PICTURES Filed July 30, 1928 2Sheets-Sheet 2 Patented Oct. 10, 1933 UNITED STATES PATENT OFFICE HenryWilliam Joy, Brooklyn, N. Y. Application July so, 1928. Serlal No.296,183

'lClaims.

My invention relates to what is popularly known as television andparticularly to the electrical transmission of visual color, whereby thereceived image appears in substantially the same colors as that of theoriginal at the moment of transmitting and receiving, life motion wherepresent is also transmitted and reproduced.

The general principles governing our conception of visible colors andthe optical illusion of color blending by persistence of direct andcomplementary color vision are well known and I apply these principlestogether with certain modifications to my invention for the electricaltransmission of visual color. The principles of persistence of directand complementary color vision have been well demonstrated and made useof in the production of moving pictures in their apparent naturalcolors.

In order to electrically transmit a focused scene, image or picture, itis necessary to split or divide the image into a multiplicity of dots orparts and transmit electrically the light intensity or value of theparts or dots, singly, in rapid and regular sequence. One or more seriesof dots or picture parts may be transmitted at one time depending uponthe number of electrical circuits or wave systems employed but in orderto better describe my invention, I will confine my description to theuse of but one circuit or wave path, altho I do not confine its use tosuch.

Before considering my invention, it must be well understood that lightor color cannot be transmitted as is, by any known electrical method;means must be employed to translate any given light or color value orintensity into an equivalent electrical value and for this purpose, itis customary to employ what is termed a photo electric cell or elementthat shall respond instantly to light or color change. In practice,there are many cells or light sensitive elements bearing the property ofchanging electrically in ratio to light changes but respond irregularlyto change of colored light and this irregularity must be taken intoconsideration when it is desired to transmit scenes in natural colors.The received image should also be illumined by colors or lights thatcollectively constitute the visible spectrum. From this, it can bereadily seen that defects existing in the transmission of colors can berectified in the receiver by employing suitable color filters or methodsfor breaking up the colors in transmission to harmonize with the colorfilters and lighting as employed in the receiver.

In transmitting a scene in colors, I use a revolving perforated disc orother scanning means bearing light filters arranged to pass the lightfrom or through one dot or picture part, once. for every color filter orunit employed, so that 00 each illumined dot 'is transmitted two or moretimes in sequence, as each illumination is passed thru color filters ofopposing value, it follows that each dot is analyzed by rapidlyalternating complementary colors or their equivalents which in turn isresolved into corresponding electrical values by the photo-electricelement. This procedure is repeated until the whole picture area hasbeen color analyzed. In constructing such a color filter disc for mypurpose, the colors selected may be, say, red-orange and blue-green, theone alternating with the other, but as the usual photo electric cell isnot generally equally sensitive to both of these colors, adjustments canbe made by varying the color densities or tones until experimentindicates the cell to be passing both opposing colors equally, this canbe readily ascertained by transmitting the light reflected from whitepaper or clear sky. Should it be desired to employ a photo electric cellthat is totally so blind to red light, or any distinctive color? thiscondition can be met by omitting the red filter entirely and so transmitby using the bluegreen or opposing filter alternating with a nonfilteredor white beam, care being taken to maintain similar light intensitieswhich can best be carried out by using a smaller hole for the white beamand adjusting the density of the blue-green or opposing filter to suit.The principles of color balancing in natural color photography are wellunderstood by those skilled in the art, and must also be applied totelevision practice with certain modifications to compensate for colorblind transmission. From this, it can be readily seen that by my methodof color transmission an approximation to natural colors can besuccessfully recorded when one major color only is transmitted; provideda diffeemtial of color values is alternately transmitted at aperiodicity well beyond persistence of color vision, any color 100compensation is possible by the selection of suitable color filters forthe receiver, ,i. e., should a red ray be missing in the transmitter, itcan be supplied by the receiver, simply because in television actualcolors are not transmitted.

In selecting the colors for my receiving filters I use preferablyred-orange and blue-green, and a white light as illuminant, same beingmodified by the picture current actuating a light valve or other-meansof light modulation. 110

It must be understood that synchronous operation of transmitter andreceiver must be maintained, otherwise picture distortion and colorreversals will take place, i. e., transmitted red will be received asgreen and so on.

Another adaptation of my method of color transmission may be utilized bythe employment of but one color only alternating with a balanced whitebeam and used in receiving; in this instance, a fair approximation tovisual natural colors is obtained by complementary color vision. It iswell known that when the eye is bombarded by a rapidly occurring color,a sense of complementary color is aroused and. the real and the assumedcolors will harmonize to produce a sensation of color unity. It will benoted there are many modifications of my invention, any. of which may beutilized to assist in overcoming the color deficiencies existing in thevarious light recording and producing elements.

Reference to my drawings will more clearly describe my invention. Fig. 1illustrates the transmitting and receiving discs which are identical indesign and as applied to my method using two opposing or complementarycolors, such as redorange and blue-green.

Fig. 2 illustrates the transmitting and receiving discs as applied to mymethod of using one color only alternating with a balanced non-filteredlight.

Fig. 3 illustrates the transmitting and receiving discs which areidentical in design, as applied to my method of using more than twocolors for the entire color range transmission.

Fig. 4 is a diagrammatic showing of an apparatus which may be used fortransmitting.

Fig. 5 is a similar view illustrating one embodiment which may be usedfor receiving.

On referring again to Fig. 1, as an illustration, G denotes green and Rdenotes red. C is the natural center of the disc. Taking G I and R I asbeing the first pair of colors, it will be noted that both areequi-distant from the center C, this applies to each pair of colors onthe disc and each pair such as G2 and R2 and so on is located insequence nearer the center C. It is understood that when using one wavetransmission one hole only can be transversing the picture area at onemust be provided to cover the entire picture area before the leadinghole GI is again in location.

The colored light filters may be small pieces of suitably coloredgelatine individually secured to the respective holes. The regularapproach of each pair of holes toward the center C is equal to theapproximate diameter of one hole. It is desirable that all holes in Fig.1 and Fig. 3 are of the same diameters in each individual disc.

The disc Fig. 2 is similar to the disc Fig. 1 with the exception of thediameters of the holes, it is preferable to have the color filteredholes R in Fig. 2 of larger diameter than the open holes W, as in thisdisc if all holes were of same diameter the non-filtered holes W wouldpass a greater volume of light than the filtered holes R, for whichcompensation is made by making the W holes of a smaller diameter thanthe R holes. The object sought in each application of my invention is totransmit and so receive equal alternating light intensities of eachcolor employed; as is well known, the sum total of equal intensities ofred-orange and blue-green, is white light, therefore should one color bemore intense than its complementary, such color will predominate of anyset being equi-distant from the center C.

Fig. 4 illustrates one method of transmitting when applying my inventionfor color analysis of the object (1" which may be an image, picture, orscene. e is a condensing lens whose function is to throw a condensedimage upon the disk ,f, same being an edge view of either Fig. 1, 2, or3, as required according to the color sensitiveness of the cell h; g isa synchronous motor in phase with the receiving motor 1, Fig. 5; h. is alight sensitive cell having a preferred range of constant sensitivenessto all visible colors; i is the customary transmitting apparatusreceiving the amplified current values-as emitted by the cell h throughthe customary amplifying circuits.

Fig. 5 illustrates one method of receiving when applying my inventionfor the viewing of received images in colors. "7 is a customary radioreceiving set feeding the Kerr cell 0; k is an edge view of either Fig.1, 2, or 3, as required to agree with the transmission characteristicsof the cell 71. and disk "1", Fig. 4; Z is a synchronous motor in phasewith the motor g, Fig. 4; m is a screen upon which the image isreceived; is a magnifying lens; "0 is a Kerr cell, containing polarizingprisms and usual magnetic field rotation coil; p is a collimeter lens,whose function is to throw a parallel beam of white light from the lamp"q, through the Kerr cell, rotating disk, lens, and on to screen m; q isa high intensity lamp or source of white light; r is a reflector toassist the lens p. The Kerr cell as here indicated, functions as a whitelight transmission valve, but other means may be so employed.

Figs. 4 and 5 together illustrate my invention as applied to theemployment of but one wave band. A plurality of wave bands may beemployed by repeating the procedure for every wave band, as required.

In using my method of transmitting alternating colors, the lightreceiving element or cell as located in the transmitter should beresponsive as far as possible to the entire range of visible spectrumcolors, it is, however, possible to provide compensation if necessary byvarying the colors of the filters actually employed; in transmitting,the question of correct colors being used is immaterial as any lightsensitive cell can only register varying light intensities; it istherefore in practice the function of the transmitting disc to simplypass onto the light cell opposing light values of balanced intensitieswhich it does by being provided with alternating colors or holes ofvarying areas, alternating with balanced color filtered light beams.

In receiving, the colored picture is reconstructed for direct vision.The source of light used for receiving should be the equivalent of whitelight and the receiving color disc should be provided with coloredfilters that are substantially correct, i. e., the sum total of allcolored lights when passed equally by the respective receiving discshould be apparently white. For instance, when the source of light inthe receiver is deficient in producing the entire spectrum colors, thedisc or principles of Fig. 2 may be used to advantage and the sense ofcomplementary color vision relied upon to produce apparent colorharmony.

It must be well understood that with so many types of light recordingand reproducing cells, tubes or elements at disposal, a selection shouldbe made to meet the required conditions of color transmission as nearlycorrect as the varying characteristics will permit. An idealphotosensitive cell for transmitting would be one with equalsensitiveness to all visible colors and an ideal source of light forreceiving would be a pure white light which obviously would contain allvisible colors equally. Failing the ideal, compensation can be effectedby resorting to careful color balancing as already indicated.

For the sake of convenience, I shall employ the term object in theclaims, although, in so doing, it is to be understood that I do not usethis the same distance from the center of the disk word in a technicalsense as contrasted to an image, but intend by the word object to coverwhat in the art are usually termed objects and images or in fact anyoptical field.

Whilst I have disclosed but a single embodiment of my invention, it iscapable of modification therefrom without departure from the spirit andscope thereof, and it is desired therefore that only such limitationshall be imposed on the appended claims as are required by the priorart, or indicated therein.

I claim as my invention:

1. In a picture transmitting system, a scanning member having aplurality of sets of openings therein, all openings in a set beingadapted to transmit the same beam of light, and one of said openingstransmitting white light and the other a color, said second-namedopening being larger than the first-named one.

2. In a picture transmitting or receiving system, a scanning memberhaving a multiplicity of openings therein so arranged in a series thatan object is scanned in sequence through said openings, said openingshaving color filters associated therewith and the filters oversuccessive openings being arranged in successive sets, with theaggregate components of all filters in any set giving to the eyesubstantially the impression of natural color, and the filters in anyone set scanning the same area of the object.

3. In a picture transmitting or receiving system, a rotatable scanningdisk having a multiplicity of openings therein so arranged in a se riesthat upon rotation of the disk an object is scanned in sequence throughsaid openings, said openings being arranged in successive sets in theseries, with the openings in each set adapted to transmit difierentlight components and with the aggregate of the components transmitted byall openings in any set giving to the eye substantially the impressionof natural color, and the openings in any one set scanning substantiallythe same area.

4. In a picture transmitting or receiving system, a rotatable scanningdisk having a multiplicity of openings therein so arranged in a seriesthat upon rotation of the disk an object is scanned in sequence throughsaid openings, said openings being arranged in successive sets in theseries, with the openings in each set adapted to transmit differentlight components and with the aggregate of the components transmitted byall openings in any set giving to the eye substantially the impressionof natural color, all openings in each set being disposed atsubstantially and the openings in difierent sets being disposed atdifierent distances from said center.

5. In a picture transmitting or receiving system, a rotatable scanningdisk having a multiplicity of openings therein so arranged in a seriesthat upon rotation of the disk an object is scanned in sequence throughsaid openings, said openings being arranged in successive sets in theseries, said sets being located upon arcs of concentric circles with theradiiof said arcs progressively decreasing from one end of the series tothe other, and with all the openings in any given set disposed on one ofsaid arcs.

6. In a picture transmitting or receiving system, a rotatable scanningdisk having a multiplicity of openings therein so arranged in a seriesthat upon rotation of the disk an object is scanned in sequence throughsaid openings, said openings being arranged in successive sets in theseries, said sets being located upon arcs of concentric circles with theradii of said arcs progressively decreasing from one end of the seriesto the other, all the openings in any given set being disposed on one ofsaid arcs and the openings in each set being adapted to transmitdifferent light components, the aggregate of the components transmittedby all openings in any set giving to the eye substantially theimpression of natural color.

7. The method of electrical transmission or reception of a picture whichcomprises successively scanning difierent small areas of an object, eacharea being scanned in succession by light components of different valueswhose resultant gives to the eye substantially the impression of naturalcolor.

HENRY WILLIAM JOY.

